- The exciting chemistry of tetraazidomethane
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(Chemical Equation Presented) With a nitrogen content of 93.3%, "perazidomethane(CN12) is highly explosive but nevertheless isolable. The title compound, which is accessible from commercially available trichloroacetonitrile in one step, undergo
- Banert, Klaus,Joo, Young-Hyuk,Rueffer, Tobias,Walfort, Bernhard,Lang, Heinrich
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p. 1168 - 1171
(2008/03/15)
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- Free and metal-coordinated (N-isocyanimino)triphenylphosphorane: X-ray structures and selected reactions
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An improved procedure for the synthesis of (N-isocyanimino)- triphenylphosphorane, C≡N-N=PPh3 (3), is described. The X-ray structure analysis reveals an unusually small N-N=P angle [115.2(2)°] and an N-N bond order of only about 1.5, which indicates considerable C≡N-N --P+ participation and electronically more-isolated functional groups (CN, P=N) in the isocyanide than, for example, in the isomeric N≡C-N=PPh3 (4) [C-N=P = 123.0(4)°, C-N bond order = 2.0]. In order to gain insight into the stereochemical consequences of metal coordination of 3, an X-ray structural study of [Cr-(CO)5C≡N-N= PPh3] (5) was also undertaken. Surprisingly, the central bond lengths (C-N, N-N) and angles (C-N-N) remain practically unchanged with noticeable coordination effects occurring only at the periphery of 5, with the N-N-P angle [112.3(2)°] further decreased by 15σ, the elongated (by 7σ) P-N bond, the somewhat shortened (by 4σ) P-C(Ph) bonds and even shorter C-H(Ph) bonds on the one side, and the well-known Cr-C(O)trans contraction on the other. Treatment of 5 or its tungsten derivative with anhydrous Bronstedt and Lewis acids such as CF3COOH, HCl, COS, phosgene or, most efficiently, [PdCl2(1,5-COD)] causes CN→NC isomerisation to give [M(CO)5N≡C-N=PPh3] [M = Cr (6), W (7)]. In solution, [PdCl2(CNNPh3)2] and Ph3BCNNPPh3 (8) slowly isomerize even without additional acid to give both free and Pd-coordinated 4 and Ph3BNCNPPh 3 (9), respectively. In the presence of catalytic amounts of [PdCl2(1,5-COD)], 3 is converted into 4 and the dimer Ph 3PN-C(CN)=N-NPPh3 (10) in an almost 1:1 ratio. The optimised geometries of the methyl derivatives of 3 and 4, namely Me 3P=N-N≡C (3c) and Me3P=N-C≡N (4c), are in excellent agreement with the experimental data; major differences between the isomers (P-N-N angle, N-N bond length) are explained by the higher electronegativity of the isocyano group as compared to the CN substituent, which, in turn, is a better π-acceptor). The reaction path of the isomerisation of 3 to 4 (3c to 4c) has also been studied computationally and been found to proceed via an [(P)=NA-N≡CA(N A-CA)] cyclic transition state. The overall process is exothermic by 50 kcal mol-1. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
- Stolzenberg, Heribert,Weinberger, Bernd,Fehlhammer, Wolf Peter,Puehlhofer, Frank G.,Weiss, Robert
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p. 4263 - 4271
(2007/10/03)
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- In situ generation of 2,3-diaryltetrazolinlidenes: Trapping experiments and ring opening to 1-cyanoazimines
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The redox system formazanide ion/tetrazolium ion, realized as an ECE sequence, is as a to manipulate both electron-deficient and -surplus centers attached to the of electronically. In order to introduce this redox substituent as a nucleophilic entity into
- Lowack, Rainer H.,Weiss, Robert
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p. 333 - 338
(2007/10/02)
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- Reactions of bis(trimethylsilyl)isocyanamide and its isomers with chlorotriphenylphosphonium chloride: evidence for a transient dizomethylenetriphenylphosphorane. Crystal structure of NN->2
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Triphenylphosphine dichloride reacts with (Me3Si)2C=NN, Me3SiN=C=NSiMe3, and metal-coordinated CN-N(SiMe3)2 to give the iminophosphoranes CN-NPPh3, NC-NPPh3, and W(CO)5CN-NPPh3, respectively, and with free bis(trimethylsilyl)isocyanamine to give a dicatio
- Zinner, Gerhard,Beck, Gerhard,Fehlhammer, Wolf P.,Wiberg, Nils
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- Synthesis of Bis(phospha-λ5-azenes) by a Redox-Condensation Reaction. Formation of an Anomalous N-Cyanophospha-λ5-azene from Urea
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The reaction of diphosphines with sulfonamides, a phosphinamide, and cyanamide as well as of a dicarboxamide, a disulfonamide, urea, thiourea, and sulfamide with triphenylphosphine in the presence of diethyl azodicarboxylate has
- Bittner, Shmuel,Pomerantz, Martin,Assaf, Yonit,Krief, Penina,Xi, Shikang,Witczak, Malgorzata K.
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- Formation and Thermal Cleavage Reactions of the Cycloadduct of 9,10-Dimethylanthracene and Nitrosyl Cyanide
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Nitrosyl cyanide and 9,10-dimethylanthracene (DMA) (2) reacted at -25 deg C to form the crystallyne cycloadduct, 9,10-dihydro-9,10-(N-cyanoepoxyimino)-9,10-dimethylanthracene (1).The adduct (1) decomposed in the presence of the conjugated diene thebaine (3), to form DMA(2) and the adduct (4) of nitrosyl cyanide and thebaine.First-order kinetics, k = 6.9E-5 s-1, were observed for the release of DMA in benzene at 40 deg C, consistent with slow dissociation of the adduct (1) followed by rapid capture of nitrosyl cyanide by thebain.A similar first-order rate, k = 6.8E-5 s-1, was observed for the reaction of the adduct (1) and triphenylphosphine (2 mol equiv.) under the same conditions, the products being DMA, triphenylphosphine oxide, and triphenylphosphine N-cyanoimide (5).The reactions of nitrosyl cyanide, generated thermally from the adduct (1), were studied with a range of dienes.The conjugated dienes, N-cyanomethyl-N-northebaine (3; NCH2CN replacing NMe), trans,trans-1,4-diphenylbuta-1,3-diene (6; R=H), and ergosteryl acetate (11) all gave the expected cycloadducts (3,6-dihydro-2H-1,2-oxazines).Norbornane gave the tetracyclic adduct (10) arising from 1,4-conjugate addition of nitrosyl cyanide.The reactions of the adduct (1) with tetraphenylcyclopentadienone (14), 1,3-diphenylisobenzofuran (18), 2-methyl-1,3-diphenylisoindole (23), diazofluorene (24), and diphenyldiazomethane all took a more complex course leading in each case to the formation of an N-cyano-ketimine (alkylidene-cyanamide)
- Horsewood, Peter,Kirby, Gordon W.,Sharma, Ram Prakash,Sweeny, James
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p. 1802 - 1806
(2007/10/02)
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